Deep Learning
A Generative Map for Image-based Camera Localization
Guo, Mingpan, Matthes, Stefan, Ye, Jiaojiao, Shen, Hao
In image-based camera localization systems, information about the environment is usually stored in some representation, which can be referred to as a map. Conventionally, most maps are built upon hand-crafted features. Recently, neural networks have attracted attention as a data-driven map representation, and have shown promising results in visual localization. However, these neural network maps are generally hard to interpret by human. A readable map is not only accessible to humans, but also provides a way to be verified when the ground truth pose is unavailable. To tackle this problem, we propose Generative Map, a new framework for learning human-readable neural network maps, by combining a generative model with the Kalman filter, which also allows it to incorporate additional sensor information such as stereo visual odometry. For evaluation, we use real world images from the 7-Scenes and Oxford RobotCar datasets. We demonstrate that our Generative Map can be queried with a pose of interest from the test sequence to predict an image, which closely resembles the true scene. For localization, we show that Generative Map achieves comparable performance with current regression models. Moreover, our framework is trained completely from scratch, unlike regression models which rely on large ImageNet pretrained networks.
Matrix and tensor decompositions for training binary neural networks
Bulat, Adrian, Kossaifi, Jean, Tzimiropoulos, Georgios, Pantic, Maja
This paper is on improving the training of binary neural networks in which both activations and weights are binary. While prior methods for neural network binarization binarize each filter independently, we propose to instead parametrize the weight tensor of each layer using matrix or tensor decomposition. The binarization process is then performed using this latent parametrization, via a quantization function (e.g. sign function) applied to the reconstructed weights. A key feature of our method is that while the reconstruction is binarized, the computation in the latent factorized space is done in the real domain. This has several advantages: (i) the latent factorization enforces a coupling of the filters before binarization, which significantly improves the accuracy of the trained models. (ii) while at training time, the binary weights of each convolutional layer are parametrized using real-valued matrix or tensor decomposition, during inference we simply use the reconstructed (binary) weights. As a result, our method does not sacrifice any advantage of binary networks in terms of model compression and speeding-up inference. As a further contribution, instead of computing the binary weight scaling factors analytically, as in prior work, we propose to learn them discriminatively via back-propagation. Finally, we show that our approach significantly outperforms existing methods when tested on the challenging tasks of (a) human pose estimation (more than 4% improvements) and (b) ImageNet classification (up to 5% performance gains).
Disentangling Pose from Appearance in Monochrome Hand Images
Li, Yikang, Twigg, Chris, Ye, Yuting, Tao, Lingling, Wang, Xiaogang
Hand pose estimation from the monocular 2D image is challenging due to the variation in lighting, appearance, and background. While some success has been achieved using deep neural networks, they typically require collecting a large dataset that adequately samples all the axes of variation of hand images. It would, therefore, be useful to find a representation of hand pose which is independent of the image appearance~(like hand texture, lighting, background), so that we can synthesize unseen images by mixing pose-appearance combinations. In this paper, we present a novel technique that disentangles the representation of pose from a complementary appearance factor in 2D monochrome images. We supervise this disentanglement process using a network that learns to generate images of hand using specified pose+appearance features. Unlike previous work, we do not require image pairs with a matching pose; instead, we use the pose annotations already available and introduce a novel use of cycle consistency to ensure orthogonality between the factors. Experimental results show that our self-disentanglement scheme successfully decomposes the hand image into the pose and its complementary appearance features of comparable quality as the method using paired data. Additionally, training the model with extra synthesized images with unseen hand-appearance combinations by re-mixing pose and appearance factors from different images can improve the 2D pose estimation performance.
Deep Neural Network Based Hyperspectral Pixel Classification With Factorized Spectral-Spatial Feature Representation
Chen, Jingzhou, Chen, Siyu, Zhou, Peilin, Qian, Yuntao
Deep learning has been widely used for hyperspectral pixel classification due to its ability of generating deep feature representation. However, how to construct an efficient and powerful network suitable for hyperspectral data is still under exploration. In this paper, a novel neural network model is designed for taking full advantage of the spectral-spatial structure of hyperspectral data. Firstly, we extract pixel-based intrinsic features from rich yet redundant spectral bands by a subnetwork with supervised pre-training scheme. Secondly, in order to utilize the local spatial correlation among pixels, we share the previous subnetwork as a spectral feature extractor for each pixel in a patch of image, after which the spectral features of all pixels in a patch are combined and feeded into the subsequent classification subnetwork. Finally, the whole network is further fine-tuned to improve its classification performance. Specially, the spectral-spatial factorization scheme is applied in our model architecture, making the network size and the number of parameters great less than the existing spectral-spatial deep networks for hyperspectral image classification. Experiments on the hyperspectral data sets show that, compared with some state-of-art deep learning methods, our method achieves better classification results while having smaller network size and less parameters.
Counterfactual Visual Explanations
Goyal, Yash, Wu, Ziyan, Ernst, Jan, Batra, Dhruv, Parikh, Devi, Lee, Stefan
A counterfactual query is typically of the form 'For situation X, why was the outcome Y and not Z?'. A counterfactual explanation (or response to such a query) is of the form "If X was X*, then the outcome would have been Z rather than Y." In this work, we develop a technique to produce counterfactual visual explanations. Given a 'query' image $I$ for which a vision system predicts class $c$, a counterfactual visual explanation identifies how $I$ could change such that the system would output a different specified class $c'$. To do this, we select a 'distractor' image $I'$ that the system predicts as class $c'$ and identify spatial regions in $I$ and $I'$ such that replacing the identified region in $I$ with the identified region in $I'$ would push the system towards classifying $I$ as $c'$. We apply our approach to multiple image classification datasets generating qualitative results showcasing the interpretability and discriminativeness of our counterfactual explanations. To explore the effectiveness of our explanations in teaching humans, we present machine teaching experiments for the task of fine-grained bird classification. We find that users trained to distinguish bird species fare better when given access to counterfactual explanations in addition to training examples.
NYU open-sources breast cancer screening model trained on over 200,000 mammography exams
Breast cancer is the second leading cancer-related cause of death among women in the U.S. It's estimated that in 2015, 232,000 women were diagnosed with the disease and approximately 40,000 died from it. And while diagnostic exams like mammography have come into wide practice -- in 2014, over 39 million breast cancer screenings were performed in the U.S. alone -- they're not always reliable. About 10 to 15 percent of women who undergo a mammogram are asked to return following an inconclusive analysis. That's why researchers at New York University are investigating an AI-driven technique that promises much higher precision than today's tests. In a newly published paper on Arxiv.org
AI defeated a top-tier 'Dota 2' esports team
So much for the best Dota 2 players having the skill to fend off cutting-edge AI. OpenAI Five has beaten five players from OG, the veteran team that won Valve's 2018 International, in a best-of-three exhibition match. The Verge noted that the deep learning system thrived by relying on aggressive and unconventional methods, including instant revivals for heroes in the early stages, and picking valuable heroes. While OG put up a fight (the first round lasted over 30 minutes), it couldn't hold out. OpenAI also used the exhibition to show that Five could play alongside human players and learn from their play styles.
Faster, more accurate diagnoses: Healthcare applications of AI research
When Google DeepMind's AlphaGo shockingly defeated legendary Go player Lee Sedol in 2016, the terms artificial intelligence (AI), machine learning and deep learning were propelled into the technological mainstream. AI is generally defined as the capacity for a computer or machine to exhibit or simulate intelligent behaviour such as Tesla's self-driving car and Apple's digital assistant Siri. It is a thriving field and the focus of much research and investment. Machine learning is the ability of an AI system to extract information from raw data and learn to make predictions from new data. Deep learning combines artificial intelligence with machine learning.
Exploiting Event Log Data-Attributes in RNN Based Prediction
Hinkka, Markku, Lehto, Teemu, Heljanko, Keijo
In predictive process analytics, current and historical process data in event logs are used to predict future. E.g., to predict the next activity or how long a process will still require to complete. Recurrent neural networks (RNN) and its subclasses have been demonstrated to be well suited for creating prediction models. Thus far, event attributes have not been fully utilized in these models. The biggest challenge in exploiting them in prediction models is the potentially large amount of event attributes and attribute values. We present a novel clustering technique which allows for trade-offs between prediction accuracy and the time needed for model training and prediction. As an additional finding, we also found that this clustering method combined with having raw event attribute values provides even better prediction accuracy at the cost of additional time required for training and prediction. We also built a highly configurable test framework that can be used to efficiently evaluate different prediction approaches and parameterizations.
LeanResNet: A Low-cost yet Effective Convolutional Residual Networks
Ephrath, Jonathan, Ruthotto, Lars, Haber, Eldad, Treister, Eran
Convolutional Neural Networks (CNNs) filter the In recent years there has been an effort to reduce the number input data using a series of spatial convolution of parameters in CNNs. Among the first approaches are operators with compact stencils and point-wise the methods of pruning (Hassibi & Stork, 1992; Han et al., non-linearities. Commonly, the convolution operators 2015; Li et al., 2017) and sparsity (Wen et al., 2016; couple features from all channels, which Changpinyo et al., 2017; Han et al., 2016) that have been leads to immense computational cost in the training typically applied to already trained full networks. It has of and prediction with CNNs. To improve been shown that once a network is trained, a large portion the efficiency of CNNs, we introduce lean convolution of its weights can be removed without hampering its operators that reduce the number of parameters efficiency by much.